I am not particularly well read in this area, but from what i do know, I think that it wouldn't do you any harm. The only drawback of creatine is that due to it's osmotic properties it can cause dehydration, so you'd have to make sure you drink loads of water, preferably with electrolytes (so you don't get sodium/pottasium imbalance).
Creatine can also cause diarrhea when not well absorbed, again due to osmotic pressure, so if you had an iffy stomach it might be better to skip it.
As far as weight gain powders high in protein, I can't see how they are much different to high nitrogen feeds so as long as you get enough fluids and eat enough fibre, then they would be a good way to gain lots of muscle with your weightlifting.
Good luck and hope you see some huge strength gains!